paper

The first bird's-eye view of a gravitationally unstable accretion disk in high-mass star formation

arXiv:1905.12983 · doi:10.3847/2041-8213/ab212f

Abstract

We report on the first bird's-eye view of the innermost accretion disk around the high-mass protostellar object G353.273+0.641, taken by Atacama Large Millimter/submillimeter Array long-baselines. The disk traced by dust continuum emission has a radius of 250 au, surrounded by the infalling rotating envelope traced by thermal CHOH lines. This disk radius is consistent with the centrifugal radius estimated from the specific angular momentum in the envelope. The lower-limit envelope mass is 5-7 M and accretion rate onto the stellar surface is 3 10 M yr or higher. The expected stellar age is well younger than 10 yr, indicating that the host object is one of the youngest high-mass objects at present. The disk mass is 2-7 M, depending on the dust opacity index. The estimated Toomre's parameter is typically 1-2 and can reach 0.4 at the minimum. These values clearly satisfy the classical criteria for the gravitational instability, and are consistent with the recent numerical studies. Observed asymmetric and clumpy structures could trace a spiral arm and/or disk fragmentation. We found that 70 of the angular momentum in the accretion flow could be removed via the gravitational torque in the disk. Our study has indicated that the dynamical nature of a self-gravitating disk could dominate the early phase of high-mass star formation. This is remarkably consistent with the early evolutionary scenario of a low-mass protostar.

Accepted to ApJL, 11 pages, 3 figures, 2 tables

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